Re: [PATCH] arch/arm64 :Cyclic Test fix in ARM64 fpsimd

[Anders Roxell <anders.roxell@xxxxxxxxxx>]

On 2015-05-01 20:59, Ayyappa Ch wrote:
> Floating point operations in arm64 should not disable preempt .

I thought that I would see a problem if I ran a floating point
workload and cyclictest at the same time but I don't.

Can you please provide me some more details on how I can reproduce the
problem?

Cheers,
Anders

> Activating realtime features with below code.
> 
> From e6a5fce9b3b55f48656240036a9354a0997c2907 Mon Sep 17 00:00:00 2001
> From: Ayyappa Ch <ayyappa.chandolu@xxxxxxx>
> Date: Tue, 28 Apr 2015 11:53:00 +0530
> Subject: [PATCH ] floating point realtime fix
> 
> ---
>  arch/arm64/kernel/fpsimd.c | 16 ++++++++--------
>  1 file changed, 8 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
> index 2438497..3dca156 100644
> --- a/arch/arm64/kernel/fpsimd.c
> +++ b/arch/arm64/kernel/fpsimd.c
> @@ -166,10 +166,10 @@ void fpsimd_flush_thread(void)
>   */
>  void fpsimd_preserve_current_state(void)
>  {
> - preempt_disable();
> + migrate_disable();
>   if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
>   fpsimd_save_state(&current->thread.fpsimd_state);
> - preempt_enable();
> + migrate_enable();
>  }
> 
>  /*
> @@ -179,7 +179,7 @@ void fpsimd_preserve_current_state(void)
>   */
>  void fpsimd_restore_current_state(void)
>  {
> - preempt_disable();
> + migrate_disable();
>   if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
>   struct fpsimd_state *st = &current->thread.fpsimd_state;
> 
> @@ -187,7 +187,7 @@ void fpsimd_restore_current_state(void)
>   this_cpu_write(fpsimd_last_state, st);
>   st->cpu = smp_processor_id();
>   }
> - preempt_enable();
> + migrate_enable();
>  }
> 
>  /*
> @@ -197,7 +197,7 @@ void fpsimd_restore_current_state(void)
>   */
>  void fpsimd_update_current_state(struct fpsimd_state *state)
>  {
> - preempt_disable();
> + migrate_disable();
>   fpsimd_load_state(state);
>   if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
>   struct fpsimd_state *st = &current->thread.fpsimd_state;
> @@ -205,7 +205,7 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
>   this_cpu_write(fpsimd_last_state, st);
>   st->cpu = smp_processor_id();
>   }
> - preempt_enable();
> + migrate_enable();
>  }
> 
>  /*
> @@ -239,7 +239,7 @@ void kernel_neon_begin_partial(u32 num_regs)
>   * that there is no longer userland FPSIMD state in the
>   * registers.
>   */
> - preempt_disable();
> + migrate_disable();
>   if (current->mm &&
>      !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
>   fpsimd_save_state(&current->thread.fpsimd_state);
> @@ -255,7 +255,7 @@ void kernel_neon_end(void)
>   in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
>   fpsimd_load_partial_state(s);
>   } else {
> - preempt_enable();
> + migrate_enable();
>   }
>  }
>  EXPORT_SYMBOL(kernel_neon_end);
> 
> On Fri, May 1, 2015 at 1:03 PM, Ayyappa Ch <ayyappa.ch.linux@xxxxxxxxx> wrote:
> > Following Anders Roxell  patch on "Enable PREEMPT_RT_FULL" , observed
> > one issue with Cyclic test while running floating point operations. So
> > , modified below changes for that.
> >
> > From e6a5fce9b3b55f48656240036a9354a0997c2907 Mon Sep 17 00:00:00 2001
> > From: Ayyappa Ch <ayyappa.chandolu@xxxxxxx>
> > Date: Tue, 28 Apr 2015 11:53:00 +0530
> > Subject: [PATCH ] floating point realtime fix
> >
> > ---
> >  arch/arm64/kernel/fpsimd.c | 16 ++++++++--------
> >  1 file changed, 8 insertions(+), 8 deletions(-)
> >
> > diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
> > index 2438497..3dca156 100644
> > --- a/arch/arm64/kernel/fpsimd.c
> > +++ b/arch/arm64/kernel/fpsimd.c
> > @@ -166,10 +166,10 @@ void fpsimd_flush_thread(void)
> >   */
> >  void fpsimd_preserve_current_state(void)
> >  {
> > - preempt_disable();
> > + migrate_disable();
> >   if (!test_thread_flag(TIF_FOREIGN_FPSTATE))
> >   fpsimd_save_state(&current->thread.fpsimd_state);
> > - preempt_enable();
> > + migrate_enable();
> >  }
> >
> >  /*
> > @@ -179,7 +179,7 @@ void fpsimd_preserve_current_state(void)
> >   */
> >  void fpsimd_restore_current_state(void)
> >  {
> > - preempt_disable();
> > + migrate_disable();
> >   if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
> >   struct fpsimd_state *st = &current->thread.fpsimd_state;
> >
> > @@ -187,7 +187,7 @@ void fpsimd_restore_current_state(void)
> >   this_cpu_write(fpsimd_last_state, st);
> >   st->cpu = smp_processor_id();
> >   }
> > - preempt_enable();
> > + migrate_enable();
> >  }
> >
> >  /*
> > @@ -197,7 +197,7 @@ void fpsimd_restore_current_state(void)
> >   */
> >  void fpsimd_update_current_state(struct fpsimd_state *state)
> >  {
> > - preempt_disable();
> > + migrate_disable();
> >   fpsimd_load_state(state);
> >   if (test_and_clear_thread_flag(TIF_FOREIGN_FPSTATE)) {
> >   struct fpsimd_state *st = &current->thread.fpsimd_state;
> > @@ -205,7 +205,7 @@ void fpsimd_update_current_state(struct fpsimd_state *state)
> >   this_cpu_write(fpsimd_last_state, st);
> >   st->cpu = smp_processor_id();
> >   }
> > - preempt_enable();
> > + migrate_enable();
> >  }
> >
> >  /*
> > @@ -239,7 +239,7 @@ void kernel_neon_begin_partial(u32 num_regs)
> >   * that there is no longer userland FPSIMD state in the
> >   * registers.
> >   */
> > - preempt_disable();
> > + migrate_disable();
> >   if (current->mm &&
> >      !test_and_set_thread_flag(TIF_FOREIGN_FPSTATE))
> >   fpsimd_save_state(&current->thread.fpsimd_state);
> > @@ -255,7 +255,7 @@ void kernel_neon_end(void)
> >   in_irq() ? &hardirq_fpsimdstate : &softirq_fpsimdstate);
> >   fpsimd_load_partial_state(s);
> >   } else {
> > - preempt_enable();
> > + migrate_enable();
> >   }
> >  }
> >  EXPORT_SYMBOL(kernel_neon_end);
> > --
> > 1.9.1
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